Athos is a new process combining HTO with biological treatment, which mineralises the organic matter in the sludge under moderate conditions of temperature (235°C) and pressure (45 bar) in the presence of pure oxygen.

Athos generates 3 stable and/or recyclable byproducts:

• Clean gas emission,
• A biodegradable organic liquid,
• A primarily mineral-based solid.

An environmentally friendly process

Athos is a clean technology : all the sludge components are recycled, recovered or discharged to the natural environment with no adverse effects.

• Final result : a concentrate of inorganic matter (technosand) accounting for only 1% to 2% of the quantity of initial liquid sludge ;
• Possibility of recycling the technosand for building materials ;
• Stabilisation of the heavy metals in the solid residue in a non-leachable form (inert waste) ;
• Zero emissions of polluted fumes nor harmful by-products (nitrogen oxides, dioxins, furans) ;
• Reduction of the greenhouse effect (50% drop in CO2 emissions compared with incineration) ;
• Destruction of toxic and malodorous (hydrogen sulphide, mercaptan, etc.) and organic micropollutants.

A flexible process
Athos provides high operational flexibility :

• Treats all types of thickened sludge ;
• Possibility of adjusting retention time, temperature and the O2/organic pollution ratio ;
• Advanced automation.

A cost-effective thermal process
Operating costs are reduced by:

• Moderate operating conditions (temperature and pressure, limited O2 consumption) ;
• Reducing the dewatering stage (restricted only to the inorganic fraction of the sludge), with no chemicals addition.

A compact process
Thanks to its compact design, Athos can be fully integrated into the wastewater treatment plant and provides continuous sludge processing, as well as its by-products treatment.

With less than an hour retention time in the reactor, the ATHOS process results in:

• high mineralization (less than 5% organic carbon content in the solid residue),
• an easily biodegradable liquid that can be returned to the biological treatment process (equivalent to  15% total COD* in the sludge),
• continuous and safe oxidation, under continuous mixing,
• phase separation between gas and inorganic sludge. The heat released by the oxidation reaction is recovered to heat the sludge, with no external energy supply